1. FIELD OF THE INVENTION
The present invention relates to a contact charger for use in image forming apparatus such as electrophotographic copying apparatus, printers and the like.
2. DESCRIPTION OF THE RELATED ART
In image forming apparatus such as electrophotographic copying apparatus, printers and the like, an image carrier such as a photosensitive drum and the like is electrically charged by a charging device, and an optical image is exposed on the charged area of the image carrier to form an electrostatic latent image thereon. This latent image is then developed so as to be rendered visible, transferred onto a transfer sheet and fused thereon.
Notable among charging devices of the aforesaid type are contact chargers which produce much less ozone than do conventional corona chargers.
Chargers of the contact type have certain disadvantages in that some use a charging brush which is difficult to fabricate, and some use a charging roller which is not only difficult to manufacture because it requires a driving means, but may also develop "creep" deformation distortion resulting from contact of the charging roller with the image carrier when the image forming apparatus is stopped, thereby causing inadequate charging. Blade type contact chargers are disadvantageous in that the blade is difficult to set with precision. Furthermore, a strong blade coming into contact with the surface of the image carrier may result in damage to the image carrier, and a large torque is necessary to rotate the image carrier. Contact chargers which use a rotating type endless belt for charging tend to enlarge the apparatus overall, and pose a further complexity of a belt drive method.
Contact chargers are difficult to manufacture, complex in construction, and enlarge the apparatus. The complexity of the charger driving means is currently a significant obstacle hindering the production of compact, low cost image forming apparatus.